A submersible boom that includes: a support system containing a substantially horizontal support member; a boom curtain formed of a flexible fabric material, the boom curtain being suspended from the substantially horizontal member; and means for raising and lowering the substantially horizontal support member between first (with the substantially horizontal support member at least partially above the surface of a body of water) and second (submerged) positions. Use of the boom in accordance with a method of allowing boat traffic ingress into and egress from a region within a body of water is also disclosed.